Many vaporizers have been proposed that use electrical power or solid or liquid fuel to vaporize herbal substances such as tobacco or medical marijuana. These vaporizers have the advantage of vaporizing the herbal substance without combustion, thereby avoiding the combustion that has negative health and environmental results, as well as creating a fire hazard. Typically, these vaporizers have an herbal chamber where the herbal material is placed and heating elements that either surround the herbal chamber on the outside, or have coils that spiral within the herbal chamber. The herbal chamber has an herbal chamber cavity that extends the length of the herbal chamber. Other heating mechanisms are also used, where heated air may be forced through the chamber. In addition, many have a flat screen on its mouthpiece end that prevents the herbal substance from being entering the mouthpiece.